Combining object arrays

[mike]

If I have 2 object arrays like:

var txtobj = theform.getElementsByTagName("input");
var selobj = theform.getElementsByTagName("select");

and i want to iterate over them I'd like to combine them and then
iterate over them.

so I would do something like this below, but that doesn't look right.
var bothobj = txtobj+selobj;

for( var i=0; i<bothobj.length; i++ )
{
do something....
}

Any thought?

[Randy Webb]

mike said the following on 9/14/2005 4:37 PM:

Test it and see.

.concat()

--
Randy
comp.lang.javascript FAQ - http://jibbering.com/faq & newsgroup weekly

[Mick White]

mike wrote:

> If I have 2 object arrays like:
>
> var txtobj = theform.getElementsByTagName("input");
> var selobj = theform.getElementsByTagName("select");

Bad!!
var txtobj = document.theform.getElementsByTagName("input")

But why not use DOM 0?

function checkInputsAndSelects(form){
var f=form.length;
while(f--){
if(form[f].type.toLowerCase()=="input"){
// do stuff with input
}
if(form[f].type.toLowerCase()=="select"){
// do stuff with select
}
}
}

Mick

[...]

[mike]

Mick,

Why is this bad?

var txtobj = document.theform.getElementsByTagName("input")

Is it because you think it only gets <input ..> but not <INPUT ...>

Mike

[Mick White]

mike wrote:

var txtobj = theform.getElementsByTagName("input");

missing "document" reference...

Will work in IE, though.

Mick

[mike]

i had already defined

var theform = document.update;

so ... it is ok then ... ?

[RobG]

mike wrote:
> If I have 2 object arrays like:
>
> var txtobj = theform.getElementsByTagName("input");
> var selobj = theform.getElementsByTagName("select");
>
> and i want to iterate over them I'd like to combine them and then
> iterate over them.
>
> so I would do something like this below, but that doesn't look right.
> var bothobj = txtobj+selobj;

No, it's not right. getElementsByTagName returns an HTML collection,
not an array. Collections have some array-like properties, e.g. length,
but have none of an Array's methods.

>
> for( var i=0; i<bothobj.length; i++ )
> {
> do something....
> }

To concatenate collections, you could create a concatenation function
that adds the elements of a collection to an array[1]:

function concatCollections() {
var c, k, j, i = arguments.length;
var a = [];
for ( j=0; j<i; j++ ) {
c = arguments[j];
h = c.length;
for ( k=0; k<h; k++ ){
a.push(c[k]);
}
}
return a;
}

And once you've created the collections, call the above function:

var arrayOfElements = concatCollections(txtobj, selobj);

But this seems a waste of time. Whatever function that is going to
iterate over the array could accept multiple arguments and iterate over
collections instead.

Unless there are some array methods you'd like to use.

[1] Push is not supported in very old browsers (it was introduced in
JavaScript 1.2, works in Netscape 3+ and IE 5+ I think), it's pretty
simple to create your own push function if required.
<URL:http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Global_Objects:Array:push>

--
Rob

[Mick White]

mike wrote:

Your original post:

<QUOTE>

If I have 2 object arrays like:

var txtobj = theform.getElementsByTagName("input");

var selobj = theform.getElementsByTagName("select");

[...]
</QUOTE>

Missing "document" reference.
Mick

[mike]

But this seems a waste of time. Whatever function that is going to
iterate over the array could accept multiple arguments and iterate over

collections instead.

I agree. thanks though for your explanation and collection code.

Mike

[mike]

This is what I decided to do:

var theform = document.update;

var txtobj = theform.getElementsByTagName("input");

var mod = do_something(txtobj);
... something happens with the results of mod

var selobj = theform.getElementsByTagName("select");

var mod = do_something(selobj);

... something happens with the results of mod

function do_something(obj)
{
for( var i=0; i<obj.length; i++ )
{
do something....
return .....
}
}

Mike